Unraveling the Electron Transport Propellant Mechanism of Oxygen Vacancy for Boosting Hydrogen Evolution Electrocatalysis in Alkaline Seawater

Abstract Currently, hydrogen evolution reaction (HER) in alkaline seawater still faces problems such as low catalyst activity and Cl⁻ poisoning of active sites. In this work, an electron transfer facilitator of oxygen vacancies is introduced as a driving force for electronic transmission, which enhances the electron‐metal‐support interactions (EMSI) effect while introducing a charge protective layer, realizing killing two birds with one stone. In situ characterizations and density functional theory (DFT) calculations demonstrate that the EMSI effect enhances the H^* transfer step at the interface. At the same time, due to oxygen vacancies for the enhanced EMSI, Ru forms an electron‐rich layer, avoiding the poison of Cl⁻ on active sites in seawater for HER. As a result, the Ru/Ni(OH)_2‐x has an overpotential of only 156 mV at a current density of 1.0 A cm⁻² in alkaline seawater. After assembling anion‐exchange‐membrane water electrolyzers (AEMWE), the Ru/Ni(OH)_2‐x has a flat efficiency of ≈70% at different current densities, low energy consumption and price of per gallon gas equivalent (GGE) H₂ produced. Owning to the well Cl⁻ tolerance, the catalyst also maintains long‐term stability at 0.5 A cm⁻², indicating its great potential for industrial feasibility.